Package structure for photonic transceiving device

ABSTRACT

A photonic transceiver apparatus in Quad Small Form-factor Pluggable (QSFP) package. The apparatus includes a case having a base member, two partial side members, and a lid member to provide a spatial volume with an opening at a back end of the base member. Additionally, the apparatus includes a printed circuit board (PCB), installed inside the spatial volume over the base member having a pluggable electrical connector at the back end. Further, the apparatus includes multiple optical transmitting devices in mini-transmit-optical-sub-assembly package, each being mounted on a common support structure and having a laser output port in reversed orientation toward the back end. Furthermore, the apparatus includes a silicon photonics chip, including a fiber-to-silicon attachment module, mounted on the PCB and coupled to a modulation driver module and a trans-impedance amplifier module. Moreover, the apparatus includes a pair of optical input/output ports being back connected to the fiber-to-silicon attachment module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 14/793,636 filed Jul. 7, 2015, commonly assignedand incorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

The present disclosure is related to a photonic transceiver packagestructure, more particularly, to a silicon photonic transceiver packagestructure which conforms to the Quad Small Form-factor Pluggable (QSFP)specification adapted for multiple mini-transmit optical sub-assembly(TOSA) laser devices disposed with output in opposite direction relativeto transceiver module optical input/output port.

As science and technology are updated rapidly, processing speed andcapacity of the computer increase correspondingly. The communicationtransmission or reception using the traditional cable is limited tobandwidth and transmission speed of the traditional cable and massinformation transmission required in modern life causes the traditionalcommunication transmission overload. To correspond to such requirement,the optical fiber transmission system replaces the traditionalcommunication transmission system gradually. The optical fibertransmission system does not have bandwidth limitation, and also hasadvantages of high speed transmission, long transmission distance, itsmaterial not interfered by the electromagnetic wave. Therefore, presentelectronic industrial performs research toward optical fibertransmission which will become the mainstream in the future. Saidoptical communication is a technology in that light wave functions assignal carrier and transmitted between two nodes via the optical fiber.Field of the optical communication can be divided into opticalcommunication side and electric communication side according totransmission medium. By the optical transceiver, the received opticalsignal can be converted to an electrical signal capable of beingprocessed by an IC, or the processed electrical signal can be convertedto the optical signal to be transmitted via optical fiber. Therefore,objective of communication can be achieved.

Wavelength-division multiplexing (WDM) is a multitask technology ofprocessing multiple optical carrier signals transmitted by the opticalfiber, and this technology is applied on the different wavelength signalor transmission of laser optical source. This technology is implementedin both directions on the optical fiber to double total transmissioncapacity. Besides, the term “wavelength-division multiplexing” is mostlyapplied in optical carrier, and frequency-division multiplexing isapplied in radio carrier. Moreover, both of wavelength and frequency arein reciprocal relationship, so their concept can be applied to eachother.

Wavelength-division multiplexing is implemented by dividing the workwavelength of optical fiber into multiple channels to enable mass datatransmission in one optical fiber. A whole wavelength-divisionmultiplexing (WDM) system can be divided into a wavelength divisionmultiplexer at transmitting end and a wavelength division demultiplexerat receiving end. At present, there are commercial wavelength divisionmultiplexer/demultiplexer which can divide 80 or more channels in theoptical fiber communication system, so that the data transmission speedcan exceed grade of Tb/s effectively.

In both transmitting and receiving ends of the optical fibercommunication system, the transmitting module adapted for WDMtechnology, the connector usually has single light transmitterstructure. However, such light transmitter structure can emit opticalsignals with different frequencies, but cannot be repaired forindividual frequency. Therefore, whole light transmitter must bereplaced if being damaged, and it causes larger consumption in cost.

BRIEF SUMMARY OF THE INVENTION

The present disclosure is related to a photonic transceiver packagestructure, more particularly, to a silicon photonic transceiver packagestructure that conforms to the QSFP specification adapted with multiplemini-TOSA laser devices disposed with output in opposite directionrelative to transceiver optical input/output port. In certainembodiments, the invention is applied for high bandwidth opticalcommunication, though other applications are possible.

In modern electrical interconnect systems, high-speed serial links havereplaced parallel data buses, and serial link speed is rapidlyincreasing due to the evolution of CMOS technology. Internet bandwidthdoubles almost every two years following Moore's Law. But Moore's Law iscoming to an end in the next decade. Standard CMOS silicon transistorswill stop scaling around 5 nm. And the internet bandwidth increasing dueto process scaling will plateau. But Internet and mobile applicationscontinuously demand a huge amount of bandwidth for transferring photo,video, music, and other multimedia files. This disclosure describestechniques and methods to improve the communication bandwidth beyondMoore's law.

Serial link performance is limited by the channel electrical bandwidthand the electronic components. In order to resolve the inter-symbolinterference (ISI) problems caused by bandwidth limitations, we need tobring all electrical components as close as possible to reduce thedistance or channel length among them. Stacking chips into so-called 3-DICs promises a one-time boost in their capabilities, but it's veryexpensive. Another way to achieve this goal in this disclosure is to usemultiple chip module technology.

In an example, an alternative method to increase the bandwidth is tomove the optical devices close to electrical device. Silicon photonicsis an important technology for moving optics closer to silicon. In thispatent application, we will disclose a high speed electrical opticsmultiple chip module device to achieve terabits per second speed, aswell as variations thereof.

In a specific embodiment, the present invention provides a photonictransceiver apparatus in QSFP package. The apparatus includes a case,comprising a base member, two partial side members being connected by ajoint piece and coupled to the base member, a lid member including acover coupled to the two partial side members. The base member is toprovide a spatial volume with an opening at a back end of the basemember. Additionally, the apparatus includes a printed circuit board(PCB), installed inside the spatial volume over the base member. The PCBincludes a board body extended from a front edge to a back edge. Theback edge is near the opening at the back end of the base member and theboard body includes an array of metallic pin stripes at the back edge toform a pluggable electrical interface connector. The apparatus furtherincludes multiple optical transmitting devices mounted in parallel on acommon support member resting on the PCB near the front edge withcorresponding laser output port aligned toward the back edge.Furthermore, the apparatus includes a silicon photonics chip, mounted onthe PCB, including a fiber-to-silicon attachment module to couple with afirst fiber from each of the laser output port. Moreover, the apparatusincludes an optical input port and an optical output port disposedtogether on a front end of the base member near the joint piece for thetwo partial side members. Each of the optical input port and opticaloutput port is back connected via a second fiber to the fiber-to-siliconattachment module.

Therefore, the present disclosure has at least following advantages.First, the package structure for the photonic transceiver of the presentdisclosure can be detached independently, so that assembly engineer canreplace single photonic transceiver in failure. Secondly, the PCB boardand cylindrical element of a transmitting laser device of the presentdisclosure can be detached and detected individually, so that thecylindrical element provided with the coupling lens can be recycled forreuse when the transmitting module is damaged. Thirdly, the reversedoutput orientation of the transmitting laser device relative to thetransceiver output port provides easy access for the laser output fiberto couple with a silicon photonics chip on the PCB.

The present invention achieves these benefits and others in the contextof known memory technology. However, a further understanding of thenature and advantages of the present invention may be realized byreference to the latter portions of the specification and attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following diagrams are merely examples, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many other variations, modifications, and alternatives.It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this process andscope of the appended claims.

FIG. 1A is a perspective bottom view of a photonic transceiver packagestructure with lid according to an embodiment of the present invention.

FIG. 1B is a perspective top view of a photonic transceiver packagestructure with lid according to the embodiment of the present invention.

FIG. 2A is a perspective top view of a photonic transceiver packagestructure without handle part but with lid member according to theembodiment of the present invention.

FIG. 2B is a perspective top view of a photonic transceiver packagestructure without lid member according to the embodiment of the presentinvention.

FIG. 3 is a perspective top view of a photonic transceiver on a circuitboard according to the embodiment of the present invention.

FIG. 4 is a perspective bottom view of a mini-TOSA laser device for thephotonic transceiver according to the embodiment of the presentinvention.

FIG. 5 is a perspective top view of a mini-TOSA laser device for thephotonic transceiver without cover according to the embodiment of thepresent invention.

FIG. 6 is an exploded view of the mini-TOSA laser device according to anembodiment of the present invention.

FIG. 7 is a top view of the mini-TOSA laser device according to anembodiment of the present invention.

FIG. 8 is a side view of the mini-TOSA laser device according to theembodiment of the present invention.

FIG. 9 is a cross sectional view of the mini-TOSA laser device accordingto the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is related to a photonic transceiver packagestructure, more particularly, to a silicon photonic transceiver packagestructure in QSFP specification adapted with multiple mini-TOSA laserdevices disposed with reversed output orientation relative totransceiver optical input/output port. In certain embodiments, theinvention is applied for high bandwidth optical communication, thoughother applications are possible.

The following description is presented to enable one of ordinary skillin the art to make and use the invention and to incorporate it in thecontext of particular applications. Various modifications, as well as avariety of uses in different applications will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to a wide range of embodiments. Thus, the present inventionis not intended to be limited to the embodiments presented, but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to one skilled in the art thatthe present invention may be practiced without necessarily being limitedto these specific details. In other instances, well-known structures anddevices are shown in block diagram form, rather than in detail, in orderto avoid obscuring the present invention.

The reader's attention is directed to all papers and documents which arefiled concurrently with this specification and which are open to publicinspection with this specification, and the contents of all such papersand documents are incorporated herein by reference. All the featuresdisclosed in this specification, (including any accompanying claims,abstract, and drawings) may be replaced by alternative features servingthe same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

Furthermore, any element in a claim that does not explicitly state“means for” performing a specified function, or “step for” performing aspecific function, is not to be interpreted as a “means” or “step”clause as specified in 35 U.S.C. Section 112, Paragraph 6. Inparticular, the use of “step of” or “act of” in the Claims herein is notintended to invoke the provisions of 35 U.S.C. 112, Paragraph 6.

Please note, if used, the labels left, right, front, back, top, bottom,forward, reverse, clockwise and counter clockwise have been used forconvenience purposes only and are not intended to imply any particularfixed direction. Instead, they are used to reflect relative locationsand/or directions between various portions of an object.

FIG. 1A is a schematic bottom view of a photonic transceiver packagestructure with lid member according to an embodiment of the presentinvention. As shown, the photonic transceiver package structure iscompatible with the Quad Small Form-factor Pluggable (QSFP)specification, which is designed for a compact small form factor,hot-pluggable photonic transceiver package 100 used for high speed datacommunications applications. Technically, the small form factorpluggable transceiver 100 allows data rates of 4×10 Gbit/s, 4×28 Gbit/sor higher. A handle part 130 is included at the front end 105 for easyhandling of plugging or unplugging of the photonic transceiver package100 (with a photonic transceiver installed within the package structurebut not visible yet in this figure) into or out of a port ofcommunication network system terminals such as routers, switches, andtransport gears. At the same front end 105, a pair of optical ports (oneinput and out output, not visible in FIG. 1A and will be shown later) ofthe QSFP packaged transceiver are disposed.

FIG. 1B is a schematic top view of a photonic transceiver packagestructure with lid member according to the embodiment of the presentinvention. The top view shows a removable lid member 110 still beenplaced for the photonic transceiver 100 on the side members 140 of theQSFP package structure. The electrical connection on a PCB is barelyvisible at the back end 106 of the QSFP package structure for connectingwith system terminals via a simple plug-in operation.

FIG. 2A is a schematic top view of a photonic transceiver packagestructure with a lid member in position according to the embodiment ofthe present invention. This diagram is merely an example, which shouldnot unduly limit the scope of the claims. One of ordinary skill in theart would recognize many variations, alternatives, and modifications.The handle part has been removed from the package structure. FIG. 2B isa schematic top view of a photonic transceiver package structure withouthandle part and lid member according to the embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. As shown,the lid member 110 has been removed from a clip structures 145 on theside member 140 to reveal the inside package layout of the photonictransceiver 200. In an embodiment, the side member 140 has two verticalpieces coupled to side edges of a base member 120. The two verticalpieces 140 are connected by a horizontal joint piece 141 leveled withthe base member 120. The joint piece 141 is located near a front end ofthe base member 120. In another embodiment, the lid member 110 includesa cover and a pair of partial side pieces to couple with the base member120 to provide a space volume that can hold the photonic transceiver 200therein, which is revealed in FIG. 2B, while leaving an opening at aback end 106 of the base member 120.

As shown in FIG. 2B, the photonic transceiver 200 includes two opticalports 218, 219 and a PCB 220 mounted on the base member. One opticalport 218 is designed as optical input port for the transceiver 200 andanother port 219 is an optical output port. Both optical ports aredisposed in parallel along length direction near a front end region ofthe base member 120, just recessed from the horizontal joint piece 141for the side member 140. The front side of the optical input port 218and optical output port 219 are respective part of two opticalconnectors, such as typical LC connector or other suitable connectorsused in the industry. For example, a paired multi-fiber push on (MPO) orLC connector can be used, one fiber for the optical input port 218 andanother fiber for optical output port 219. Each of the paired moduleinput/output ports is back connected by an optical fiber 211 forinternal connection in the photonic transceiver 200. The PCB 220 islocated a short distance away from the two optical ports 218 and 219 andextended toward the back end 106 of the base member 120 of the photonictransceiver package 100.

Referring to FIG. 2B, additionally, several elements for the photonictransceiver 200 are mounted on the PCB 220. First of all, multipletransmitting devices 210 are grouped together and mounted near the frontpart of the PCB 220. In a specific embodiment, four such transmittingdevices are installed. In a specific embodiment, each transmittingdevice 210 is a laser device, or particularly here is a mini-TOSA (minitransmit optical sub-assembly) laser device. As shown, each mini-TOSAlaser device 210 is installed with its laser output port 215 orientatedin opposite direction of the two optical ports 218 and 219 so that eachlaser output port 215 has a fiber 212 coming out towards the back end106. The fiber 211 from the optical input/output ports 218/219 is laidunder the transmitting device 210. Both fiber 212 and fiber 211 are thenconfigured to couple with a fiber-to-silicon attachment module 231 of asilicon photonics chip 230 which is mounted in the middle of the PCB220. The silicon photonics chip 230 is coupled to two modules, a drivermodule 234 and a TIA (trans-impedance amplifier) module 235 forindependently processing electrical/optical signals of the photonictransceiver 200. Furthermore, two ASIC chips 201 and 202 are mounted onthe PCB 220 near the back edge 226 to control electrical interface forcommunication with network system via multiple metallic pin stripes 222disposed at the back edge 226 of the PCB 220, which will be accessiblefor plugging into a system apparatus through the opening near the backend 106 of the photonic transceiver package 100 when the lid member 110is placed back.

FIG. 3 is a schematic top view of a photonic transceiver without handlepart, lid member, and side members of the package structure according tothe embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. As shown, the handle part 130 and side members 140are also removed from a base member 120 of the photonic transceiverpackage. PCB 220 and a pair of optical input/output ports 218/219 forthe photonic transceiver 200 are disposed on the base member 120.

In an embodiment, the photonic transceiver 200 includes fourtransmitting devices 210 installed on the PCB 220 near its front edge225. In a specific embodiment, each of the transmitting devices 210 is amini-TOSA laser device. Each mini-TOSA laser device 210 is configured(via a transmitting module inside) to produce one laser light at aspecific wavelength belonging to coarse-wavelength-division-multiplexingchannels without any TEC module, outputted through a laser output port215 with a single-mode optical fiber 212 and is coupled into afiber-to-silicon photonics attachment module 231 pre-fabricated on thesilicon photonics chip 230 which is mounted on the middle region of PCB220. The fiber-to-silicon photonics attachment module 231 includesmultiple V-grooves for coupling the optical fibers with siliconwaveguides (not visible) through which the light received externally canbe can be directly guided to a MZ modulator per channel (not visible inFIG. 3) capable of operating under PAM4 and NRZ protocol. In otherwords, this silicon photonics chip 230 is, contrary to some conventionalphotonics chips with internal laser diodes, configured to receive lightsignal from external optical sources which are just the four mini-TOSAlaser device 210 in the implementation of the present invention shown inFIG. 3. This chip and package design make the manufacture of the siliconphotonics chip 230 independent from any tuning process of the laserdevices, thereby enhancing the robustness and reliability of the wholeQSFP transceiver package.

In a specific embodiment, there are four mini-TOSA laser devices 210 ineach QSFP package 100, which needs four MZ modulators correspondinglyfor the four channels of wavelengths of laser light. As mentioned inFIG. 2B, the silicon photonics chip 230 is coupled to the modulationdriver module 234 by wire bonding. The driver module 234 is afour-channel silicon-germanium modulator driver for driving each of thefour MZ modulators to modulate corresponding channels of laser lightwith different wavelengths into a desired optical signal. In a specificembodiment, after modulation, multiple lights with different wavelengthsfrom the four mini-TOSA laser devices 210 are multiplexed and outputtedvia the fiber-to-silicon attachment module 231 again to a single opticalfiber 211 connected to the optical output port 219 (with a LC or MPOconnector) of the photonic transceiver 200.

On the other hand, the photonic transceiver device 200 is configured toreceive optical signal via the optical input port 218 which is passedthrough a single fiber 211 to the silicon photonics chip 230 first viathe fiber-to-silicon attachment module 231. Then a demultiplexer (notvisible in FIG. 3 but built in the silicon photonics chip 230)transforms it into different channels with different wavelengths beingdetected by one or more PDs (not visible in FIG. 3) therein. Eachwavelength signal is converted into an electrical signal and furtherprocessed to a digital signal at least by the TIA module 235 that iswire bonded to the silicon photonics chip 230. Since the optical signalcontains at least four wavelengths being demultiplexed, the TIA module235 is accordingly configured to be a 4-channel TIA for processing thedigital signals for corresponding channels. Also mounted on the PCB 220near the back edge 226 includes two port interface ASIC (ASIC) chips201, 202 based on CMOS technology. One ASIC chip 201 is configured forelectrical Tx module with 4×10 G (total of 40 Gbit/s) XLAUI (40 GigabitAttachment Unit Interface) electrical interface for connecting toEthernet and 4×25 G (total of 100 Gbit/s) CAUI (100 Gigabit AttachmentUnit Interface) electrical interface, through which electrical signalcan be transmitted out to Ethernet network via multiple metallic pinstripes 222 disposed as a pluggable electrical connector at the backedge 226 of the PCB 220. Another one ASIC chip 202 is configured forelectrical Rx module with similar interfaces for receiving electricalsignals from Ethernet network.

In a specific embodiment, the silicon photonics chip 230 is coupled to atwo-channel PAM4 driver module 234 for driving two, single stage ormulti stage, MZ modulators to provide optical signal modulation. ThePAM4 driver module 234 includes a PAM encoder and a FEC encoder with CDRRx I2C interface coupled to ASIC chip 201 for converting data to opticalsignal in 4×10 G to 4×25 G rate. The PAM4 driver module 234 is based on28 nm CMOS technology. Additionally, the silicon photonics chip 230 isalso coupled to a 2-channel TIA module 235 for processing electricalsignals and converting them to digital signals. The electrical signalsare converted by one or more PDs from demultiplexed light signals out ofan incoming optical signal received from the optical input port 218. The2-channel TIA module 235, also based on CMOS technology, includes PAMADC/DSP CDR and PAM decoder with CDR Tx interface coupled to ASIC chip202 for converting optical signal to digital signal in 4×10 G to 4×25 Grate and provide electrical interface communication with Ethernetnetwork via the pluggable multiple metallic pin stripes 222.

In a specific embodiment, the mini-TOSA laser device 210 is laid in areversed configuration with the corresponding laser output port 215pointing toward the back edge 226 of the PCB 220, just opposite to thatof the conventional transceiver device whose transmitter laser outputport is pointed to the optical fiber output port 219 (with a LCconnector) near the front end 105 of the photonic transceiver package100 (see FIG. 1B). Such reversed configuration allows the built-infiber-to-silicon photonics attachment module 231 on the siliconphotonics chip 230 to directly face the laser output port 215 forproperly coupling each single-mode fiber 212 to the silicon photonicschip 230. The silicon photonics chip 230 itself can be disposed closerto the ASIC chips 201/202 near the back edge 226 of the PCB 220 forsimplification of circuit board wire bonding.

As shown in FIG. 3, all four mini-TOSA laser devices 210 are disposed ona common base structure 213 that is mounted on the PCB 220. Each laserdevice 210 is disposed in upside-down fashion with a cover member 313being rested on a flat portion of the common base structure 213 while amodule base member with its outer flat surface region facing upward (inthis particular view of FIG. 3). In an embodiment, these flat surfaceregions of the laser devices 210 are conveniently being contacted withthe lid member 110 of the transceiver package 100. As the module basemember is designed for mounting (at inner side) the laser chip, thedirect contact of the module base member (via its outer flat surfaceregion) with the lid member 110 provides desired pathway for dissipatingheat from the laser chip to the lid member 110 where an external heatsink usually is attached. Although without employing TEC devices, thepackage structure disclosed here still provide sufficient heatdissipation for the transceiver 100 equipped with four mini-TOSA laserdevices 210. The common base structure 213 also includes four raisedportions having four concave-shaped surface regions for respectivelysupporting corresponding cylindrical elements of the four mini-TOSAlaser devices 210. More details about the packaging of mini-TOSA laserdevice are given below.

In yet another specific embodiment, the photonic transceiver 200 in thisembodiment applies technology of wavelength-division multiplexing (WDM),each of the four mini-TOSA laser devices 210 uses a DFB FP laser diodechip to introduce laser light of different wavelengths. The fourmini-TOSA laser devices 210 can provides four channels of 1270 nm, 1290nm, 1310 nm, and 1330 nm in coarse wavelength division multiplexing(CWDM) spectrum which can be combined into one single-mode optical fibervia wavelength-division multiplexer for middle distance and longdistance transmission. Since the accuracy of wavelength here is notimportant, no TEC module is needed for keeping the module temperature instable range for locking the wavelength. Next, the received opticalsignal is performed a light-split process by the demultiplexer and thesplit optical signals are introduced to different channels. In thisembodiment, except WDM technology, the photonic transceiver package 100also can be applied to related optical communication technologies, suchas binary phase shift keying modulation (BPSK), quadrature phase shiftkeying modulation (QPSK), conventional/coarse wavelength divisionmultiplexing (CWDM), dense wavelength division multiplexing (DWDM), andoptical add/drop multiplexer (OADM), reconfigurable optical add/dropmultiplexer (ROADM).

FIG. 4 is a perspective bottom view of a mini-TOSA laser device for thephotonic transceiver according to the embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. As shown,mini-TOSA laser device 310 includes a module base member 311 forsupporting a transmitting module (not directly visible), a cover member313 disposed above the transmitting module, a curved circuit board 314disposed at one side of the module base member 311, and a cylindricalelement 315 mounted at another side of the module base member 311. Themodule base member 311 is made of metal material and can assist thetransmitting module mounted thereon to dissipate heat.

FIG. 5 is a perspective top view of the mini-TOSA laser device for thephotonic transceiver without cover according to the embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims. One of ordinary skill in the artwould recognize many variations, alternatives, and modifications. Asshown, with the cover member 313 being removed, the module base member311, though its outer surface facing downward, is substantially visiblewith a plane part 321, and an assembling part 322 is connected to oneend the plane part 321. The plane part 321 is configured for attaching asubmount 341 on which a transmitting module 312 is mounted and one endof the flex circuit board 314 which is bent in the middle region to haveother end with electrical connections to be leveled at a differentheight for mounting with connection spots on the PCB 220. As seen inFIG. 3 the mini-TOSA laser device 310 is mounted upside-down on the PCB220 with outer surface (not visible in this view of FIG. 5) of themodule base member 311 facing upward to be contacted with the lid memberof packaged transceiver 100. The submount 341 is usually made by highthermal conductivity material for facilitating heat dissipation from thetransmitting module on the submount through the module base member tothe lid member where external heat sink usually is attached.

Referring to FIG. 5, further, the transmitting module 312 comprises amonitor photo diode (MPD) chip 3122 on a LD-submount 3121 and a LD chip3123 disposed on the submount 341. The assembling part 322 comprises anannular positioning portion 323 vertically connected to the end of theplane part 321. A positioning groove 324 is disposed inside the annularpositioning portion 323 to allow the coupling lens 351 to be fittedtherein corresponding to the submount 341 on plane part 321 nearby. Thecoupling lens 351 is aligned via the positioning groove 324 with the LDchip 3123 of the transmitting module 312 on the submount 341 forcoupling laser light along axial direction into the cylindrical element315. The coupling lens 351 comprises a metal outer part 3511 fixedwithin the annular hole 324, and at least one convex lens or sphericallens or biconvex lens 3512, disposed inside the metal outer part 3511.During manufacturing process, filler material is sealed into a spaceover the transmitting module 312 between the cover member 313 (facingdownward in FIG. 4 and being removed in FIG. 5 with an upside-down view)and the plane part 321 of the module base member 311 by infusion orwelding, in order to achieve the objective of sealing the transmittingmodule 312. The structure of the cylindrical element 315 will bedescribed in detail in following content.

Referring to FIG. 5 again, the flex circuit board 314 comprises a boardbody 3141 bent in the middle region with a module electrical connectionside 3143 disposed on one end of the board body 3141, and a PCBelectrical connection port 3144 disposed on another end of the boardbody 3141 opposite to the electrical connection side 3143. The moduleelectrical connection side 3143 of the board body 3141 is fixed on theplane part 321 of the module base member 311 by gluing. The transmittingmodule 312 is connected electrically to the module electrical connectionside 3143 of the board body 3141 by welding or conductive epoxy. The PCBelectrical connection port 3144 is connected to the connection spots ofthe printing circuits in the PCB 220 near the front edge 225 (see FIG.3) by electrical welding, spot welding or slot connection, so as totransmit the excitation signal from the signal process module on the PCB220 to the transmitting module 312.

The cylindrical element 315 of the mini-TOSA laser device 310 is mountedon the assembling part 322 correspondingly connecting to the laseroutput port 215 (a ferrule holding the optical fiber 212 which is shownin FIG. 3 but not shown in FIG. 5. In this embodiment, the cylindricalelement 315 needs to be adjusted its parts relative to the coupling lenson both X-Y plane and Z-axis so as to properly couple the laser lightemitted from the transmitting module 312 through the cylindrical element315 and to output from laser output port 215 to the optical fiber 212.

FIG. 6 is an exploded view of the mini-TOSA laser device according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. One of ordinaryskill in the art would recognize many variations, alternatives, andmodifications. As shown, the cylindrical element 315 of the mini-TOSAlaser device 310 can be disassembled into a plane adjusting mechanismmember 3151, a light distance adjusting mechanism member 3152, anisolator 3153, and an optical fiber connection mechanism member 3154(coupled with a fiber ferrule 215) arranged in order from left to rightshown in FIG. 6. The isolator 3153, when being assembled, shall be in anaxial location surrounded mainly by the light distance adjustingmechanism member 3152 and at least partially by the optical fiberconnection mechanism member 3154. The optical fiber connection mechanismmember 3154 is configured to couple with a fiber ferrule 215 for holdingthe single mode fiber 212 (see FIG. 3). Also shown in FIG. 6, thetransmitting device 312 comprises the MPD (monitor photodiode) chip 3122and the LD chip 3123, which are respectively shown with enlarged viewand are mounted on the submount 341.

FIG. 7 and FIG. 8 are respective top view and section view (along A-Aline) of the mini-TOSA laser device according to a specific embodimentof the present invention. Please refer to FIG. 4 through FIG. 8 fordetail structure of the mini-TOSA laser device 310. Referring to FIG. 6and FIG. 7, the plane adjusting mechanism member 3151 is integrated onthe assembling part 322 by welding after coupling calibration iscompleted, and space between the plane adjusting mechanism member 3151and the assembling part 322 is sealed by infusing filler. For X-Y planecalibration, the assembling part 322 of the module base member 311comprises a first connection plane 326 disposed at one side of theannular positioning portion 323 (with the positioning groove 324 in themiddle). The plane adjusting mechanism member 3151 comprises a tubularbody 31511 and second connection plane 31512 disposed at one side of thetubular body 31511. The second connection plane 31512 corresponds to thefirst connection plane 326. During the X-Y plane coupling calibration, acalibration device is used to adjust the relative position between theplane adjusting mechanism member 3151 and the assembling part 322 toalign the tubular body 31511 with the coupling lens 351 in thepositioning groove 324 of the assembly part 322. After the calibrationis done, the first connection plane 326 is fixed on the secondconnection plane 31512 by laser spot welding, and then X-Y planecalibration is completed.

Further shown in FIG. 6, the light distance adjusting mechanism member3152 is integrated into the plane adjusting mechanism member 3151 bywelding after the coupling calibration is completed, and the spacebetween them is sealed by infusing filler. For Z-axis calibration, inthe plane adjusting mechanism member 3151, a groove track 31513 isdisposed at the side of the mechanism body 31511 opposite to the secondconnection plane 31512. The light distance adjusting mechanism member3152 comprises a body 31521 having an insert part 31522 disposed at oneside of the body 31521 and the inserted part 31522 having a proper outerdiameter operably fitting into and moving along the groove track 31513.After Z-axis calibration is completed, the light distance adjustingmechanism member 3152 is fixed on the plane adjusting mechanism member3151 by laser welding or other welding methods.

FIG. 9 is a cross-sectional view of the mini-TOSA laser device along acentral cut plane according to a specific embodiment of the presentinvention. Referring FIG. 9 for illustrating the Z-axis calibrationeasily, a distance from the LD chip 3123 of the transmitting module 312to the coupling lens 3512 is defined as L1, and a distance from thecoupling lens 3512 to the isolator 3153 is defined as L2. In thisembodiment, the LD chip 3123 is disposed directly on the submount 341 infront of the coupling lens outer part 3511. The coupling lens 3512 isembedded inside the outer part 3511 with some recessed distance.Distance L1 is fixed value for tuning optical coupling to get maximumoptical output before curing. But distance L2 from the coupling lens3512 to the isolator 3153 is adjusted according to the light distanceadjusting mechanism member 3152 and the groove track 31513 of the planeadjusting mechanism member 3151. As L1 is fixed, for better couplingefficiency, length of L2 tends towards a fixed value due to convergencecharacteristic of the coupling lens 3512. Therefore, the length of L2depends on the length of L1. For biconvex lens, such configuration mayincrease the tolerance between the light distance adjusting mechanismmember 3152 and the plane adjusting mechanism member 3151 since L2>L1 sothat difficulty in process can be reduced.

In an embodiment, the isolator 3153 is disposed mainly within the lightdistance adjusting mechanism member 3152 coupled with the optical fiberconnection mechanism member 3154. The isolator 3153 can be also disposedto connect one side of the external optical fiber, but it is not limitedthereto. Referring FIG. 9 and FIG. 6, in a specific embodiment, thelight distance adjusting mechanism member 3152 comprises a firstdisposal slot 31523 disposed at another side of the body 31521 opposingto the inserted part 31522 and the first disposal slot 31523 isconfigured to mount the isolator 3153. A second disposal slot 31524 isdisposed at the same side of the body 31521 for engaging with theoptical fiber connection mechanism member 3154. The inner diameter ofthe second disposal slot 31524 is larger than that of the first disposalslot 31523, so as to form an outer ring region for assembling theoptical fiber connection mechanism member 3154. On the other hand, theoptical fiber connection mechanism member 3154 comprises a couplingportion 31541 having a first inserted part on one side designed forfitting in the second disposal slot 31524. Additionally, the opticalfiber connection mechanism member 3154 comprises a sleeve body 31542, alight coupling channel 31543, and a positioning portion 31544. Thesleeve body 31542 is configured to couple with a second inserted part onopposite side of the coupling portion 31541. The positioning portion31544 is inserted inside the sleeve body 31542. The light couplingchannel 31543 is further inserted partially in one end of thepositioning portion 31544, located in the axial direction for lightcoupling. Another end of the positioning portion 31544 is configured forcoupling an external optical fiber (via a fiber ferrule 215 which is notshown).

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. A photonic transceiver apparatus in QSFP packagecomprising: a case, comprising a base member, two partial side membersbeing connected by a joint piece and coupled to the base member, a lidmember including a cover coupled to the two partial side members and thebase member to provide a spatial volume with an opening at a back end ofthe base member; a PCB, installed inside the spatial volume over thebase member, including a board body extended from a front edge to a backedge, the back edge being near the opening at a back end of the basemember, the board body comprising an array of metallic pin stripes atthe back edge to form a pluggable electrical interface connector;multiple optical transmitting devices mounted in parallel on a commonsupport member resting on the PCB near the front edge with correspondinglaser output port aimed toward the back edge; a silicon photonics chip,mounted on the PCB, including a fiber-to-silicon attachment module tocouple with a first fiber from each of the laser output port; an opticalinput port and an optical output port disposed together on a front endof the base member near the joint piece for the two partial side membersand respectively back connected via a pair of second fibers to thefiber-to-silicon attachment module; and a pull handle having two armscoupled to respective front ends of the two partial side members.
 2. Theapparatus of claim 1 wherein each of the optical input port and theoptical output port comprises a LC connector accessible from the frontend by an optical fiber in a mate LC connector.
 3. The apparatus ofclaim 1 wherein the optical input port and the optical output port areconfigured to fit a multi-fiber push-on (MPO) connector accessible fromthe front end by two optical fibers.
 4. The apparatus of claim 1 whereineach of the multiple optical transmitting devices comprises a modulebase member and a cover member to enclose a space for holding atransmitting module and a coupling lens, the transmitting module beingmounted on a submount disposed on the module base member and thecoupling lens being disposed on the module base member next to thetransmitting module.
 5. The apparatus of claim 1 wherein the siliconphotonics chip comprises multiple silicon-based MZ (Mach Zehnder)modulators, a plurality of photo diode detectors, a wavelength-divisionmultiplexer, and a wavelength-division demultiplexer, the multiplesilicon-based MZ modulators modulating light of different wavelengthsreceived via the fiber-to-silicon attachment module from respectivelaser output ports of the multiple optical transmitting devices, thewavelength-division multiplexer being coupled to the multiplesilicon-based linear MZ modulators to combine the light of differentwavelengths after modulation before outputting via the fiber-to-siliconattachment module to the optical output port, and thewavelength-division demultiplexer being coupled to the fiber-to-siliconattachment module to demultiplex an optical signal from the opticalinput port to a light with multiple wavelengths respectively detected bythe plurality of photo diode detectors.
 6. The apparatus of claim 1wherein the multiple optical transmitting devices comprises at leastfour laser devices in mini transmit optical sub-assembly package.
 7. Theapparatus of claim 1 further comprising a QSFP specification pluggableto network system allowing data rates of 4×10 Gbit/s, 4×28 Gbit/s orhigher.
 8. The apparatus of claim 1 wherein the multiple opticaltransmitting devices are reversely laid on the PCB such that the laseroutput ports are aiming backward from the optical input port and theoptical output port.
 9. The apparatus of claim 1 wherein thefiber-to-silicon attachment module comprises multiple V-groovesfabricated on the silicon photonics chip for coupling optical fibers tosilicon waveguides.
 10. The apparatus of claim 1 wherein the siliconphotonics chip is configured to receive multiple light signalsexternally from the multiple optical transmitting devices via thefiber-to-silicon attachment module coupled with the first fiber fromeach laser output port.
 11. The apparatus of claim 4 wherein the modulebase member comprises a plane part connected with an assembly part, theplane part having an inner flat surface for attaching the submount, theassembly part having a positioning groove configured to dispose thecoupling lens therein.
 12. The apparatus of claim 4 wherein the covermember is configured to be disposed on the common support member mountedon the PCB.
 13. The apparatus of claim 4 wherein the space comprises afiller material filled by infusion and sealed by welding.
 14. Theapparatus of claim 5 further comprising a pair of ASIC chips mounted onthe PCB near the back edge respectively coupled with a modulation drivermodule and a TIA module, both being wire bonded to the silicon photonicschip.
 15. The apparatus of claim 11 wherein each of the multiple opticaltransmitting devices further comprises a circuit board having a firstflat end region mounted on the plane part connected to a bended middleregion further connected to a second flat end region at a differentheight level with metallic pin stripes for connecting to connectionspots near the front edge of the PCB.
 16. The apparatus of claim 11wherein the transmitting module comprises a monitor photodiode (MPD)chip and a laser diode (LD) chip, both being mounted on the submountthat us attached to the module base member for the LD chip to be alignedwith the coupling lens in the positioning groove at a predeterminedfirst distance.
 17. The apparatus of claim 11 wherein the module basemember comprises an outer flat surface, opposing to the inner flatsurface, for forming a contact with the lid member to direct dissipateheat from the transmitting module to any external heat sink attached tothe lid member.
 18. The apparatus of claim 14 wherein the modulationdriver module is based on CMOS technology including a PAM encoder and aFEC encoder with 4 channels CDR Rx I2C interface to drive the multiplesilicon-based MZ modulators for modulating light from the multipleoptical transmitting devices.
 19. The apparatus of claim 14 wherein theTIA module is based on CMOS technology including PAM ADC/DSP CDR and PAMdecoder with 4 channels CDR Tx interface to provide electrical interfacecommunication with Ethernet network via the pluggable electricalinterface connector.
 20. The apparatus of claim 16 wherein each of themultiple optical transmitting devices comprises a first cylindricalmember with plane adjusting mechanism, a second cylindrical member withlight distance adjusting mechanism, an isolator, and a third cylindricalmember with optical fiber connection mechanism, the first cylindricalmember being coupled with the assembly part of the module base member,the second cylindrical member being coupled to the first cylindricalmember and mounting the isolator, the third cylindrical member beingcoupled to the second cylindrical member and having a positioningportion to hold a light coupling channel.
 21. The apparatus of claim 16wherein the LD chip comprises a FP photo diode in DFB package capable ofproducing a laser light with wavelength in one of CWDM channels selectedfrom 1270 nm, 1290 nm, 1310 nm, and 1330 nm.
 22. The apparatus of claim20 wherein the first cylindrical member comprises a coupling planeconfigured to be adjusted in X-Y plane when being attached with theassembly part to align with the coupling lens in the positioning grooveand comprises a groove track for being engaged by the second cylindricalmember.
 23. The apparatus of claim 20 wherein the second cylindricalmember comprises a body having an inserted part on a first end of thebody and a first disposal slot on the second end of the body formounting the isolator therein, the inserted part having an outerdiameter fitted with the groove track so that the inserted body part ismovable along the groove track to allow the mounted isolator to becalibrated in Z-axis with a second distance from the coupling lens, thesecond distance being larger than the first distance.
 24. The apparatusof claim 23 wherein the second cylindrical member further comprises asecond disposal slot on the second end of the body for engaging with thethird cylindrical member, the second disposal slot having an innerdiameter larger than that of the first disposal slot.
 25. The apparatusof claim 24 wherein the third cylindrical member further comprises acoupling portion engaged with the second disposal slot and another endbeing coupled with a sleeve body to enclose the positioning portion witha light coupling channel, the light coupling channel being calibratedwith the isolator and an optical fiber coupled with the positioningportion via a ferrule ring.